<html>
    <meta http-equiv="Content-Type" content="text/html"; charset="utf-8" />
    <head>
        <title>
            hello world
        </title>
    </head>

    <style type="text/css">
        h1 {
            background-color: aqua;
        }
        h2 {
            background-color: blue;
        }
        h3 {
            background-color: darkcyan;
        }
        p {
            background-color: rgb(250, 0,250);
        }
    </style>

    <body>

        <h1>这是标题1</h1>
        
    </body>
</html>